Diazotrophic growth of Rhodospirillum rubrum with 2-oxoglutarate as sole carbon source affects regulation of nitrogen metabolism as well as the soluble proteome

2-Oxoglutarate plays a central role as a signal in the regulation of nitrogen metabolism in the phototrophic diazotroph Rhodospirillum rubrum. In order to further study the role of this metabolite, we have constructed an R. rubrum strain that has the capacity to grow on 2-oxoglutarate as sole carbon source, in contrast to wild-type R. rubrum. This strain has the same growth characteristics as wild-type with malate as carbon source, but showed clear metabolic differences when 2-oxoglutarate was used. Among other things, the regulation of nitrogen metabolism is altered, which can be related to different modification profiles of the regulatory PII proteins.